/*---------------------------------------------------------------------------*\
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License
    This file is part of OpenFOAM.

    OpenFOAM is free software: you can redistribute it and/or modify it
    under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
    for more details.

    You should have received a copy of the GNU General Public License
    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.

Class
    Foam::removeFaces

Description
    Given list of faces to remove insert all the topology changes. Contains
    helper function to get consistent set of faces to remove.

    Not very well tested in parallel.

SourceFiles
    removeFaces.C

\*---------------------------------------------------------------------------*/

#ifndef removeFaces_H
#define removeFaces_H

#include "Pstream.H"
#include "HashSet.H"
#include "Map.H"
#include "boolList.H"
#include "indirectPrimitivePatch.H"

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

namespace Foam
{

// Forward declaration of classes
class polyMesh;
class polyTopoChange;
class face;
class polyTopoChangeMap;
class polyDistributionMap;

/*---------------------------------------------------------------------------*\
                         Class removeFaces Declaration
\*---------------------------------------------------------------------------*/

class removeFaces
{
    // Private Data

        //- Reference to mesh
        const polyMesh& mesh_;

        //- Cosine of angles between boundary faces. Boundary faces can be
        //  merged only if angle between faces > minCos.
        const scalar minCos_;


    // Private Member Functions

        //- Change elements in cellRegion that are oldRegion to newRegion.
        //  Recurses to cell neighbours.
        void changeCellRegion
        (
            const label celli,
            const label oldRegion,
            const label newRegion,
            labelList& cellRegion
        ) const;

        //- Changes region of connected set of faces
        label changeFaceRegion
        (
            const labelList& cellRegion,
            const boolList& removedFace,
            const labelList& nFacesPerEdge,
            const label facei,
            const label newRegion,
            const labelList& fEdges,
            labelList& faceRegion
        ) const;

        //- Get all affected faces (including faces marked for removal)
        boolList getFacesAffected
        (
            const labelList& cellRegion,
            const labelList& cellRegionMaster,
            const labelList& facesToRemove,
            const labelHashSet& edgesToRemove,
            const labelHashSet& pointsToRemove
        ) const;


        // Topological changes

            //- Debug: write set of faces to file in obj format.
            static void writeOBJ
            (
                const indirectPrimitivePatch&,
                const fileName&
            );

            //- Merge faceLabels into single face.
            void mergeFaces
            (
                const labelList& cellRegion,
                const labelList& cellRegionMaster,
                const labelHashSet& pointsToRemove,
                const labelList& faceLabels,
                polyTopoChange& meshMod
            ) const;

            //- Get patch index
            label getPatchIndex(const label facei) const;

            //- Return face with all pointsToRemove removed.
            face filterFace(const labelHashSet&, const label) const;

            //- Wrapper for meshMod.modifyFace. Reverses face if own>nei.
            void modifyFace
            (
                const face& f,
                const label masterFaceID,
                const label own,
                const label nei,
                const bool flipFaceFlux,
                const label newPatchID,

                polyTopoChange& meshMod
            ) const;


public:

    //- Runtime type information
    ClassName("removeFaces");


    // Constructors

        //- Construct from mesh and min cos of angle for boundary faces
        //  to be considered aligned. Set to >= 1 to disable checking
        //  and always merge (if on same patch)
        removeFaces(const polyMesh&, const scalar minCos);

        //- Disallow default bitwise copy construction
        removeFaces(const removeFaces&) = delete;


    // Member Functions

        //- Find faces including those with cells which have the same mastercell
        //  Given set of faces to pierce calculates:
        //  - region for connected cells
        //  - mastercell for each region. This is the lowest numbered cell
        //    of all cells that get merged.
        //  - new set of faces which contains input set + additional ones
        //    where cells on both sides would have same mastercell.
        //  Returns number of regions.
        label compatibleRemoves
        (
            const labelList& inPiercedFaces,
            labelList& cellRegion,
            labelList& cellRegionMaster,
            labelList& outPiercedFaces
        ) const;


        //- Play commands into polyTopoChange to remove faces.
        void setRefinement
        (
            const labelList& piercedFaces,
            const labelList& cellRegion,
            const labelList& cellRegionMaster,
            polyTopoChange&
        ) const;

        //- Force recalculation of locally stored data on topological change
        void topoChange(const polyTopoChangeMap&)
        {}

        //- Force recalculation of locally stored data for mesh distribution
        void distribute(const polyDistributionMap&)
        {}


    // Member Operators

        //- Disallow default bitwise assignment
        void operator=(const removeFaces&) = delete;
};


// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

} // End namespace Foam

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

#endif

// ************************************************************************* //
